I very much appreciate how this version, while different, mimics the action advantage mechanics of the hero version (Boromir).

Thematically, the first ability fits great with the defender of the Hobbits role played out in the saga expansions where this card emerged. Clearly it can be of great use in low threat decks, but often those are designed around not engaging a lot of enemies or participating in a lot of combat. However I do like the parallel to the oft equipped Gondorian Shield on the hero version. Other standard boosting effects could be considered: Arwen Undómiel, Narya, Behind Strong Walls and Blade Mastery, For Gondor!, Raiment of War play well with his ability to counterattack. Round Shield is also particularly good to keep him in the fight. (I'm omitting discussing fringe or janky shenanigan cases mostly enabled by Sword-thain).

As alluded to, it's the second ability that gets the most mileage personally; as long as he can keep taking damage he can keep readying and defending (he's almost an honorary Ent). Obviously, you're going to need healing, and lots of it. This pairs great with Elrond and any cheap repeatable healing, particularly Warden of Healing, Imladris Caregiver, or even Glorfindel. Hopefully, with Elrond around, you even got him into play via Vilya.

Some fun you can have: Ent Draught, Raiment of War and abusing Vigilant Guard, particularly good with Beorn. The rarely used Sword of Morthond is a great target for him as well.

If a quest has the potential to swarm you with a lot of medium hitting allies, Boromir can be a great defensive solution, especially if you carefully plan out the sequence of your defenses and keep sending him to the House of Healing. He certainly passes the stat points to cost ratio test. Too bad he can't be in play with a Visionary Leadership Boromir.

While I love Boromir, this ally is unfortunately harder to use than I would like. The statline is pretty great, honestly. 4 resources for 1-3-1 is a pretty common statline, although expensive in tactics. And the 4 health is almost unheard of for allies unless you're an Ent.

But the abilities are of course the real bonus. The ideal turn for our friend here would be:

1. Quest with his 1 willpower

1a. Take a point of archery damage to ready.

2. Defend against a medium hitting enemy.

2a. Take another point of damage

3. Repeat 2 and 2a?
4. Clap back with that great 3 attack.

The trick is that the key parts of this strategy are 1a and 2a, and you can't really control these things. Not every scenario has direct damage. And the defend is worse considering shadow cards. Would you rather defend a 2-3 atk enemy and hope for a strong shadow card or defend a 4-5 atk enemy and hope for a harmless shadow card (assuming his defense ability triggers)? Having him accidentally die is bad but we also can't rely on him readying for an attack necessarily.

So ultimately, I think Boromir is actually best for high direct damage scenarios, where you can get several 1 willpower 3 attack turns out of him with archery. I think you can be pretty happy with that for 4 resources. But if you're hoping for more, and trying to use him to chain defenses using his readying ability, I think that's too risky to pull off and you're better off using defensive tools on heroes